The present invention relates to a scroll-type fluid machine such as, for example, a compressor for generating high-pressure gas, compressor or expander of air conditioner refrigerator, turbine and more particularly, to a balancing weight device for use in a scroll-type fluid machine.
In scroll type fluid machines, a balancing weight is attached to the orbital scroll member of the machine, in order to obtain a force which balances the centrifugal force generated by the orbital rotary motion of the orbital scroll member during the operation of the machine. Balancing weights of the aforementioned type are described in, for example, U.S. Pat. Nos. 3,473,728; 3,802,809; 3,874,827; 3,884,599; 4,082,484; 4,325,683; 4,332,535; 4,340,339; 4,129,405; 4,192,152; and 4,199,308. A disadvantage of the proposed balancing weights resides in the fact that the balancing weight is integrally connected to the driving shaft for orbitally driving the orbital scroll member.
During the operation, the centrifugal force generated on the orbital scroll member is transmitted to the drive shaft through a bearing interposed between the orbital scroll member and the drive shaft, so as to balance the counter or balancing centrifugal force which is generated by the balancing weight integrally connected to the drive shaft. Thus, the centrifugal force generated on the orbital scroll member balances through the bearing with the balancing force generated by balancing weight. Therefore, a load of the same level as the centrifugal force is applied to the bearing interposed between the orbital scroll member and the drive shaft and also to the bearing which supports the drive shaft. Consequently, these bearings are worn down due to the heavy load in quite a short period of time so that the radius of the orbital movement of the orbital scroll member is undesirably increased beyond the preselected value.
Accordingly, it is a primary object of the invention to provide a scroll type fluid machine which can maintain the radius of orbital movement of the orbital scroll member within a preselected value.
It is another object of the invention to provide a scroll type fluid machine in which the bearing interposed between the orbital scroll member and the drive shaft, as well as at least one bearing supporting the drive shaft, are substantially freed from the centrifugal force generated on the orbital scroll member.
It is still another object of the invention to provide a scroll type fluid machine equipped with a balancing weight and, hence, suited to high-speed operation.
It is a further object of the invention to provide a scroll type fluid machine equipped with a balancing weight and suited to systems of large capacities.
To these ends, according to the invention, there is provided a scroll type fluid machine in which a balancing weight is attached to the orbital scroll member through a bearing such that the balance weight rotates in synchronism with the rotation of a crankshaft which engages with the orbital scroll member through another bearing.
The above and other objects, features and advantages of the invention will become clear from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.